This invention relates to an improved gate driving device which is used for opening and closing a flapdoor type discharge gate of a weighing cradle or hopper of the "bottom-discharge" type, which is especially useful in an automatic weighing device.
U.S. Pat. No. 4,344,492 discloses a combination weighing machine including a plurality of weighing units each having an automatically loaded and unloaded weighing cradle or hopper. This weighing hopper is of the "bottom-discharge" type and has a flapdoor type discharge gate at its bottom opening. This gate is generally driven by means of link-and-crank mechanism, such as shown in the opened Japanese utility model specification No. 50-149059. However, such prior art mechanisms have suffered from a problem of overshoot which involves unwanted time loss in operation which affects high speed operation of the device and also gives undesirable shock and vibration to the weighing unit to reduce its accuracy of measurement.
Accordingly, an object of this invention is to remove the above problem and provide an improved mechanism for driving such a gate without unwanted overshoot.